What spinal cord disorders can cause herniation with spinal cord involvement?

Spinal Cord Disorders That Can Cause Herniation with Spinal Cord Involvement

Direct Answer

Ventral (transdural) spinal cord herniation is the primary spinal cord disorder where the cord itself herniates through a dural defect, most commonly occurring in the thoracic spine and causing progressive myelopathy. 1

Primary Herniation Disorder

Idiopathic Spinal Cord Herniation (ISCH)

• The spinal cord herniates ventrally through an anterior dural defect, becoming incarcerated and causing vascular compromise and adhesions 2
• Occurs predominantly in the upper thoracic region (T3-T7 most common) 3
• Can be either congenital or acquired, with trauma being a recognized precipitating factor 4
• Presents with progressive myelopathy, often manifesting as Brown-Séquard syndrome, motor impairment, sensory deficits, and genito-sphincteric disorders 4
• MRI shows characteristic anterior displacement of the spinal cord with the cord appearing "draped" over the ventral dural defect 2

Associated Conditions That Can Accompany Cord Herniation

Transdural Disc Herniation

• Disc material can herniate through the dura simultaneously with or adjacent to spinal cord herniation 2
• This represents a rare variant where both disc and cord breach the dural barrier 2

Post-Traumatic Herniation

• Spinal trauma can create dural defects that subsequently allow cord herniation 4
• Often misdiagnosed initially, with herniation developing as a delayed complication 4

Disorders Causing Extrinsic Compression (Not True Cord Herniation)

While the question asks specifically about herniation, it's critical to distinguish true cord herniation from compression:

Degenerative Disease

• Disc herniations compress but do not herniate the cord itself 1, 5
• Median disc herniation deforms the cord into a "boomerang shape" causing central cord syndrome 6
• Paramedian herniation deforms the cord into a "comma shape" 6

Rare Conditions Mentioned Alongside Cord Herniation

• Hirayama disease (cervical flexion myelopathy) 1
• Dorsal arachnoid webs 1

Diagnostic Approach

MRI is the definitive imaging modality for identifying spinal cord herniation 1, 7

Key imaging findings include:

• Anterior displacement of the spinal cord through a dural defect 2, 4
• T2 hyperintensity within the herniated cord segment indicating myelomalacia 8
• Absence of CSF anterior to the displaced cord 3
• Characteristic "kinking" or angulation of the cord at the herniation site 2

Surgical Management

The dural sling technique is the preferred surgical approach for idiopathic spinal cord herniation 3, 2

Surgical steps include:

• Laminectomy at the suspected level 3
• Dural opening with sectioning of dentate ligaments 3
• Enlargement of the dural defect if needed to safely disengage the herniated cord 3
• Placement of a bovine pericardial or synthetic sling beneath the cord to occlude the dural hiatus 3, 2
• Expansile duraplasty 3

Avoid primary dural closure as this carries higher risk of CSF leakage and complications 3

Never perform biopsy or resection of herniated cord tissue - this is contraindicated 3

Prognostic Factors

• Approximately one-third of patients experience improvement in sensory symptoms, weakness, and spasticity postoperatively 3
• Long interval between symptom onset and surgical treatment reduces chance of significant recovery 3
• Severe pain may indicate poor prognosis 3
• Most patients achieve neurological stabilization even if complete recovery is not attained 3, 2

Critical Pitfalls

• Do not confuse cord herniation with other causes of T2 hyperintensity (demyelination, inflammation, neoplasm) on MRI 8, 7
• Postoperative imaging may continue to show cord displacement due to long-standing incarceration and adhesions 3
• The degree of radiographic abnormality does not always correlate with symptom severity 7